The invention relates to an intake manifold for a multi-cylinder internal combustion engine.
Ohrnberger et al., U.S. Pat. No. 5,901,677 (=DE 43 44 504) discloses an intake manifold system for a multi-cylinder internal combustion engine having a tubular intake distributor from which extend first intake tubes that lead to the individual cylinders. Second, shorter individual intake tubes also extend from the intake distributor and open into the associated individual intake tubes. The intake distributor and the first and second intake tubes form a one-piece component which has a longitudinal bore that intersects the second individual intake tubes for the cylinders. A drum controller with an opening for each second individual intake tube is inserted into this longitudinal bore. By rotating the drum controller, this opening can be brought into or out of alignment with the respective second individual intake tube.
The tightness of the drum controller, however, can be ensured only by using additional sealing elements, e.g., seal rings or seal cages. During assembly, however, these sealing elements can get tangled which makes assembly more difficult. Furthermore, the design and production of these sealing elements requires a high measure of care and tuning to achieve the required sealing force. In addition, chattering of the drum controller cannot be excluded.
Spannbauer, U.S. Pat. No. 6,092,499 (=DE 195 39 078) discloses an intake manifold for an internal combustion engine with an engine-side flange. This engine-side flange is connected with intake pipes that proceed from a plenum and with the cylinder head flange. The engine-side flange is provided with mounting bushings for mounting to the cylinder head flange. The plenum is partitioned by an adjustable partitioning element, which can separate or connect the intake pipe plenum and thereby influences the charging effect of the cylinders. The engine-side flange is used to mount the intake manifold to the cylinder head flange. This component is bulky, however, and increases the weight of the parts. In addition, it increases assembly complexity because several components are used. Due to this additional complexity and the greater number of individual components, the component costs of this intake manifold are higher.
German patent application no. DE 195 390 424 discloses an intake manifold for an internal combustion engine with an engine-side flange. This engine-side flange is connected with intake pipes that proceed from a plenum and with the cylinder head flange. The engine-side flange is provided with mounting bushings for mounting to the cylinder head flange. The plenum is partitioned by an adjustable partitioning element, which can separate or connect the intake pipe plenum and thereby influences the charging effect of the cylinders. The engine-side flange is used to mount the intake manifold to the cylinder head flange. This component is bulky, however, and increases the weight of the parts. In addition, it increases assembly complexity because several components are used. Due to this additional complexity and the greater number of individual components, the component costs of this intake manifold are higher.
It is the object of the present to provide an improved intake manifold for a multi-cylinder internal combustion engine.
Another object of the invention is to provide an intake manifold for an internal combustion engine which reduces the clearance required in the engine compartment.
A further object of the invention is to provide an intake manifold for an internal combustion engine which can be manufactured and installed in a cost-effective manner.
It is also an object of the invention to provide an intake manifold for an internal combustion engine which can be assembled in a relatively simple manner.
These and other objects are achieved in accordance with a first aspect of the present invention by providing an intake manifold for a multi-cylinder internal combustion engine, the manifold comprising an intake distributor; a plurality of adjacent first individual intake tubes extending from the intake distributor and each extending to a respective cylinder of the engine; a plurality of second, shorter individual intake tubes extending from the intake distributor and each opening into a respective first individual intake tube; a control element for blocking or unblocking the second individual intake tubes, the control element comprising at least two flaps arranged on a common shaft surrounded by flap frames and disposed in a common control element frame; the control element being installed as a complete unit in a sealed manner in the intake manifold; and the shaft with the flaps surrounded by flap frames and the control element frame being manufactured by assembly injection molding.
In accordance with a further aspect of the invention, the objects are achieved by providing an intake manifold for a multi-cylinder internal combustion engine comprising an intake distributor; a plurality of individual intake tubes each having a cross-section and extending from the intake distributor and ending in at least one cylinder head flange; and a control element for blocking or unblocking at least a part of the cross sections of the individual intake tubes, the control element comprising at least two flaps arranged on a common shaft surrounded by flap frames and disposed in a common control element frame; the control element being installed as a complete unit in a sealed manner in the intake manifold; and the shaft with the flaps surrounded by flap frames and the control element frame being manufactured by assembly injection molding.
The control element according to the invention comprises flaps that are arranged on a shaft and are installed in a common control element frame. Flaps in this connection should be understood as sealing elements in a wider sense, particularly rotary flaps and slide valves that are adjusted in translatory manner. This control element is constructed as a complete unit, which is installed in the intake manifold forming a seal. Since each flap has only a small circumferential surface that contacts the surrounding component, the effective seal length is very small. By arranging the flaps on a continuous shaft, the shaft can be supported directly in the control element frame without requiring any additional bearings and connecting points between the flaps. As a result, the control element is suitable even for small clearances.
Advantageously, the control element is inserted and fastened in a cavity in the intake manifold. This simplifies assembly and makes it possible to replace the control element if necessary.
Another embodiment provides for direct injection molding of the intake manifold onto the control element. This makes it possible to dispense with a mounting unit, sealing means and the assembly process.
In a further embodiment of the insertion of the control element in the intake manifold, the intake manifold is accomplished by disposing the control element between two molded halves so as to form a seal, e.g., by screwing or snapping it together with one of the halves. The two molded halves are then joined, e.g., screwed together, using a seal.
In one specific embodiment, the molded halves are welded together with the control element. In this case, the control element is disposed in a holder and the intake manifold halves are then welded together so as to form a seal. This fixes the control element within the intake manifold. In this type of an embodiment the control element is inserted into the holder in such a way that there is no leakage between the components. This embodiment moreover eliminates a sealing system between the intake manifold halves.
An alternative solution to the object of the invention is an intake manifold with an intake distributor, individual intake pipes proceeding therefrom, and a control element. The control element is disposed as a complete unit in a receptacle or holder on the intake manifold and adjoins the cylinder head flange. The control element serves to block or unblock a cross-sectional flow area. Several variants to unblock this cross-sectional flow area are feasible, e.g., complete unblocking of a flow area formed by the individual intake pipes. Partial unblocking of the flow area is also feasible, however, in which case an angular momentum that influences the filling ratio of the individual cylinders can be produced by the opening position of the flap.
Another variant is to use two cross-sectional flow areas adjoining the same individual intake pipe, so that the total flow area can be increased or decreased as needed. If one flow area is blocked completely, the air must flow through the other flow area. By opening the closed flow area, the total flow area of the individual intake pipe is increased so that more air can flow through it. The receptacle or holder for the control element on the intake manifold is configured in such a way that the control element forms a seal when installed. The control element forms the connection between the intake manifold and the cylinder head flange. The intake manifold does not need to have any contact points with the cylinder head flange.
A further embodiment of the invention envisions a connecting or attachment surface of the intake manifold disposed against the cylinder head flange. In this case, the holder for the control element is configured in such a way that the connecting surface is formed onto the holder and the connecting surface of the intake manifold adjoins the cylinder head flange.
In accordance with a further embodiment of the intake manifold, mounting bushings are installed on the control element. These mounting bushings are made of a material that does not relax, e.g., metal or ceramic. The mounting bushings can subsequently be introduced into the control element, particularly into the control element frame. The mounting bushings can either be pressed into or cast in the control element. Another option of introducing the mounting bushings into the control element is to place the bushings in a mold cavity and then injection mold the control element around them.
One advantageous embodiment of the inventive concept is to insert the flaps in a flap frame, which makes it possible to adjust the play or leakage of the flaps within the flap frame. This unit is then inserted in the control element frame.
In one specific embodiment of the invention, a control element frame is used which is made of metal. In this embodiment, the mounting bushings can be formed directly on the control element frame or introduced as an additional component. Other variants of the invention provide mounting points and holders, for instance for a drive unit for the control element or for an exhaust gas recirculation unit.
It is advantageous to insert the flaps in the flap frame using an assembly injection molding technique. This ensures a cost-effective and optimum fit of the flaps within the flap frame.
Another variant uses a metal shaft to which the flaps are mounted. Under heavy mechanical loads, a metal shaft cannot be deformed as easily as a shaft made of synthetic resin material, i.e, plastic. The flaps can be made, for example, of synthetic resin material injection molded onto the shaft in an injection molding process, or they can be made of metal and can, for instance, be screwed, riveted or welded to the shaft.
It is advantageous to insert the shaft together with the flaps into the control element frame by clipping or screwing the shaft into holders that are provided for this purpose. These methods are also suitable if flap frames are used. In this case, the flap frames are mounted to the control element frame. Another option, in addition to the above insertion variants, is to injection mold the control element frame around the control elements (flap, shaft and, where applicable, flap frames).
A special variant of the invention uses an assembly injection molding technique to produce the shaft with the flaps and the control element frame. In this case, the flap frame, if present, can be produced at the same time. In an embodiment without flap frames, the control element frame performs the function of the flap frames.
In accordance with another embodiment of the invention, the flaps are comprised of one or more slide valves that are arranged on a shaft. These slide valves are displaced in a translatory movement longitudinally of the shaft, which causes the openings in the intake ports to be opened or closed. This embodiment again has the above-described advantages of reduced space requirement. If there are several slide valves, they must be coupled together along the shaft to enable a single drive unit to displace all of the slide valves. It is particularly advantageous, however, to combine the individual slide valves into a single large slide valve, which is held in the form of a plate inside the flap frame and can be centrally controlled by the drive.
The slide is advantageously made of spring steel. This spring steel can be made particularly thin and due to its elasticity can compensate certain tolerances in the area of the control element frame. Tolerances that are transferred to the control element frame as the control element frame is assembled can also be compensated by the slide valve made of spring steel.
It is particularly advantageous to control and/or drive the slide with a double-acting cylinder. This can, in particular, be a pneumatic cylinder, which is moved by the pressure differences at the intake manifold. In contrast to a cylinder with a restoring spring, the double-acting cylinder has the advantage that it does not need to produce the actuating force against the spring force. This reduces the actuating forces that must be produced by the pressure differences.
These and other features of preferred embodiments of the invention, in addition to being set forth in the claims, are also disclosed in the specification and/or the drawings, and the individual features each may be implemented in embodiments of the invention either alone or in the form of subcombinations of two or more features and can be applied to other fields of use and may constitute advantageous, separately protectable constructions for which protection is also claimed.